Chynewalker

I picked this up off eBay a couple months ago and just got around to updating it and putting it together. It came with the original MRP Mercury, but with parts for those being made of unobtainium, I decided to go with the readily available Graupner GTX 650. The outboards are about the same dimensions and configuration, so it was an easy swap. Also did away with the original micro-switch & servo set-up and installed a Traxxas Nautica ESC. Currently running it on 7.2V as that's all the ESC is rated for. Not sure how it will handle overvolting - anyone familiar with the limitations of the Nautica? I do have a watercooling add-on for it that currently is not in place (ESC is slightly warm to the touch after a 10 minute run).

When it hits a patch of calm water, it lays right out, so I think I have the set-up pretty close for what it is. Currently running the stock 650 prop - a 31mm dia, 4mm shaft plastic prop - no idea of the pitch. I will be getting an adapter to run 3/16 shaft props here shortly so I can experiment a bit.
http://www.dailymotion.com/video/xdq...at-with-g_tech

I love how it handles! This is only my third boat and easily the fastest one so far (I know, slow by FE standards, but I'm having fun!!)

Chynewalker

Just checked the Tower site and their specs for the Nautica say it's for 4.8 to 8.4 V, so I guess it won't hurt to bump it up a bit.

Also thinking about what motors I could use on this outboard. Graupner makes a 12V Speed 600 Turbo. The boat was originally designed for 14.4V - I would think the 12V motor could handle a 2 more cells, maybe? I'm trying to stick with old tech stuff due to budgetary constraints. Any suggestions for an ESC that could handle that - also keeping in mind the budgetary thing...

Thanks!

ryanwilson277

you should look on hobbyking for a brushless setup under 80 dollars

eboat

Looking at the vid can you move any of the weight farther forward to see if it would stop the bouncing ?

Chynewalker

I trimmed the motor down a little bit more and added an 8.4V battery pack to the mix this weekend. Seems to like the changes as it hops less, although a lot of it has to do with the near constant low rollers we have here - part of life on the River. Took some more video: www.dailymotion.com/video/xdrnek_mrp-bud-light-tunnel-with-graupner_tech. The best pass is at about 1:45. It's going fast enough now that I hooked it in a turn and barrel rolled it! Got it dried out and back on the water fairly quickly, although the receiver needed further attention after it started glitching. Much better now, though...

SV27dayton

Is that a turn fin on the bottom of the hull?

Chynewalker

Yes... It was on there when I bought the boat...

Chynewalker

I did some prop testing while on vacation last week and have it performing considerably better. Started with the stock 3-blade 31mm prop. The 30mm 3-blade ventilated too easily, even with the motor all the way down on the transom. The 33mm 3-blade ended up being the best performer so far. I really like how it performs now!
Fresh video:
http://www.youtube.com/watch?v=KGXIpgyeADQ